Computer systems, from small handheld electronic devices to medium-sized mobile and desktop systems to large servers and workstations, are becoming increasingly pervasive in our society. Computer systems typically include one or more processors. A processor manipulates and controls the flow of data in a computer by executing instructions. To provide more powerful computer systems for consumers, processor designers strive to continually increase the operating speed of the processor. Unfortunately, as processor speed increases, the power consumed by the processor tends to increase as well. Historically, the power consumed by a computer system has been limited by two factors. First, as power consumption increases, the computer tends to run hotter, leading to thermal dissipation problems. Second, the power consumed by a computer system may tax the limits of the power supply used to keep the system operational, reducing battery life in mobile systems and diminishing reliability while increasing cost in larger systems.
One method of reducing the amount of electric power drawn by a computer system is to design the system such that it is capable of operating in two different modes. In a first mode of operation, only the most vital functions of the system, such as those dedicated to monitoring for user input, are active. This may be referred to as a “sleep mode.” During the sleep mode, the computer system draws very little power from the voltage regulator (alternatively referred to as the power/voltage/Vcc supply or power/voltage/Vcc source). In a second mode of operation, the computer system is busy executing instructions to accomplish a particular task. This is referred to as the “wake mode.” During the wake mode, the computer system consumes a significant amount of power from the power supply.
Unfortunately, there is a side effect associated with switching a computer system between sleep and wake modes. The rapid change in current drawn from the power supply when the computer switches between modes causes fluctuations in the voltage supplied to the computer by the voltage regulator. Going from a wake mode to a sleep mode may cause a rapid decrease in current, resulting in an upwardly spiking voltage transient. Similarly, going from a sleep mode to a wake mode may cause a rapid increase in current, resulting in a downwardly spiking voltage transient.